1. Field of the Invention
This invention relates generally to semiconductor device assemblies. More particularly, the invention pertains to a method for producing a chip-on-board semiconductor device assembly with a heat spreading/dissipating member, and the device produced thereby.
2. State of the Art
In the design and production of modern integrated circuits (IC), an important consideration is the dissipation of heat generated in the semiconductor device. Elevated temperatures may cause irreparable damage to the semiconductor die and its electrical connections.
Various methods for preventing excessive temperatures in a semiconductor device have been in use.
Thus, for low-power devices of less than about 1 watt, the metal lead frame itself may be sufficient to dissipate generated heat. Lead frame configurations for improved heat dissipation are shown in U.S. Pat. No. 5,541,446 of Kierse, U.S. Pat. No. 4,961,107 of Geist et al., and U.S. Pat. No. 5,101,465 of Murphy.
For higher power packaged devices, a metal heat spreader may be incorporated into the package or attached to the outside of the package. Because of the generally low thermal conductivity of polymers, the heat dissipation design is more critical for polymer-packaged devices than for those packaged in ceramic or metal.
Heat spreaders/heat sinks/heat dissipaters in packaged semiconductor devices are often used to conduct heat to the exterior of the devices, either directly or via the leads. A wide variety of such is illustrated in U.S. Pat. No. 5,596,231 of Combs, U.S. Pat. No. 5,594,282 of Otsuki, U.S. Pat. No. 5,598,034 of Wakefield, U.S. Pat. No. 5,489,801 to Blish II, U.S. Pat. No. 4,024,570 of Hartmann et al., U.S. Pat. Nos. 5,378,924 and 5,387,554 of Liang, U.S. Pat. No. 5,379,187 of Lee et al., U.S. Pat. No. 4,507,675 of Fujii et al., U.S. Pat. No. 4,642,671 of Rohsler et al., U.S. Pat. No. 4,931,852 of Brown et al., U.S. Pat. No. 5,173,764 of Higgins III, U.S. Pat. No. 5,379,186 to Gold et al., U.S. Pat. No. 5,434,105 to Liou, and U.S. Pat. No. 5,488,254 to Nishimura et al.
The above-indicated references may be characterized as providing complex devices requiring difficult and/or costly processes to achieve the desired heat dissipation. Most of the references are not applicable at all to a high density device attached in a bare state to a substrate such as a circuit board.
Encapsulation compositions and methods are shown in U.S. Pat. No. 4,358,552 to Shinohara et al. and U.S. Pat. No. 5,194,930 to Papathomas et al.